Control apparatus for an electric timepiece

ABSTRACT

Control apparatus of an electric timepiece, particularly a watch, of the type including an electric motor synchronized by an oscillating device and the drive winding of said electric motor being connected in the motor circuit of a transistor, and including a member controlling the timing train of the timepiece, in which apparatus the oscillating device includes a piezoelectric crystal and a piece of magnetic material which when oscillated causes oscillation of said piezo-electric crystal, said magnetic material being disposed in proximity to the circumference of a rotor fixed for rotation with the electric motor and around the periphery of which rotor are disposed one or more permanent magnets so arranged that rotation of the rotor causes said magnetic material and said piezo-electric crystal to be oscillated, said piezo-electric crystal being connected in the control circuit of said transistor so that electric impulses from the oscillating piezo-electric crystal are superimposed on the motor circuit of said transistor.

United States Vosseller aent 1 CONTROL APPARATUS FOR AN ELECTRICTIIVIEPIECE Inventor: Gerhard Vosseler, Basel, Switzerland Assignee:Mueller 8: Co. A.G., Oberdorf, BL,

Switzerland Filed: Jan. 14, 1971 Appl. No.: 106,360

[30] Foreign Application Priority Data US. Cl. ..58/23 D, 318/129 Int.Cl. ..G04c 3/02 Field of Search ..58/23 TF, 23 A, 23 R,

[56] References Cited UNITED STATES PATENTS 4/1964 Helfner et al ..318/329 9/1969 Siefert ..3 18/330 X FOREIGN PATENTS OR APPLICATIONSFrance ..58/23 A [11] 3,726,@@ [451 Apr. 10, 1973 PrimaryExaminer-Richard B. Wilkinson Assistant Examiner-Edith C. S. JackmonAtt0meyRobert E. Burns and Emanuel J. Lobato ABSTRACT Control apparatusof an electric timepiece, particularly a watch, of the type including anelectric motor synchronized by an oscillating device and the drivewinding of said electric motor being connected in the motor circuit of atransistor, and including a member controlling the timing train of thetimepiece, in which apparatus the oscillating device includes apiezo-electric crystal and a piece of magnetic material which whenoscillated causes oscillation of said piezo-electric crystal, saidmagnetic material being disposed in proximity to the circumference of arotor fixed for rotation with the electric motor and around theperiphery of which rotor are disposed one or more permanent magnets soarranged that rotation of the rotor causes said magnetic material andsaid piezoelectric crystal to be oscillated, said piezo-electric crystalbeing connected in the control circuit of said transistor so thatelectric impulses from the oscillating piezo-electric crystal aresuperimposed on the motor circuit of said transistor.

10 Claims, 3 Drawing Figures PATENIEn APR 1 01973 SHEETIUFZPATENTEBAPRIOISYS 3 726,08O

SHEET 2 OF 2 CONTROL APPARATUS FOR AN ELECTRIC TIMEPIECE ing device andthe drive winding of the electric motor being connected in the motorcircuit of a transistor, and including a member controlling the timingtrain of the timepiece.

It is known already to have similar control apparatus in which vibratingoscillating reeds, which stabilize the speed of rotation of the motor,are fixed on the rotor of the motor. Such reeds function in a purelymechanical manner and are entirely independent of an electric circuitwhich includes a pickup winding in the baseemitter circuit of atransistor and an drive winding in the emitter-collector circuit of thetransistor.

It is also known to synchronize an electric motor by an oscillating reeddisposed not on the rotor of the motor but at the side thereof and inproximity thereto and having a permanent magnet which is magneticallyassociated with a permanent magnet disposed on the rotor.

It is an object of the invention to improve control apparatus of thetype referred to above in as much as the oscillating member not onlyassures in a purely mechanical manner the stabilization of the speed ofrevolution of the motor in proportion to the frequency of oscillationsof said oscillating member, but wherein the oscillating member alsoproduces synchronizing electric pulses in the control circuit of thetransistor in such a manner that an improved stabilization of the speedof rotation of the motor takes place by both mechanical electricalmeans.

According to the present invention there is provided control apparatusof an electric timepiece, particularly a watch, of the type including anelectric motor synchronized by an oscillating device and the drivewinding of said electric motor being connected in the motor circuit of atransistor, and including a member controlling the timing train of thetimepiece, in which apparatus the oscillating device includes apiezo-electric crystal and a piece of magnetic material which whenoscillated causes oscillation of said piezo-electric crystal, saidmagnetic material being disposed in proximity to the circumference of arotor fixed for rotation with the electric motor and around theperiphery of which rotor are disposed one or more permanent magnets soarranged that rotation of the rotor causes said magnetic material andsaid piezo-electric crystal to be oscillated, saidpiezo-electric-crystal being connected in the control circuit of saidtransistor so that electric impulses from the oscillating piezo-electriccrystal are superimposed on the motor circuit of said transistor.

When the apparatus of the invention is functionning one obtains theadvantage in that the motor vibrates the oscillating device by theinteraction of the magnets turning with the rotor of the motor and themagnetic material of the oscillating device resulting in that the motorrapidly obtains a constant speed of rotation which depends on thefrequency of oscillation of the oscillating device. This frequency isstabilized still further by the synchronization pulses introduced intothe control circuit of the motor and produced by the piezo-electriccrystal. Also the present invention enables the pickup winding of themotor to be dispenced with, which winding was previously necessary,because its function is assumed by the piezo-electric crystal. However,it is always possible to utilize the present invention with apparatushaving a pickup winding of the motor connected parallel or in serieswith the piezoelectric crystal.

Three forms of the present invention are hereinafter described by way ofexample only, reference being made to the accompanying drawing, in whichFIG. 1 is a schematic circuit diagram of a first form of the invention,and

FIG. 2 is a schematic circuit diagram of a second form of the invention,

FIG. 3 is a schematic diagram of a third form of the invention.

Referring first to FIG. 1, a rotor 2 having permanent magnets 3 disposedregularly about its circumference is secured on the shaft 1 of a motor.To one side of the rotor 2 and in close proximity thereto is situated anoscillatable member in the form of a metallic reed 4 the lower end ofwhich is embedded in a support 8. Such support, for example, may consistof the mounting plate of a watch or of a stud fixed to such mountingplate. The reed 4 carries at its free end a permanent magnet 6 sodisposed as to be in close proximity to the circumference of the rotor2. Instead of the magnet 6 it is possible to use a piece of soft steel.Attached to the reed 4 is a pawl 5 in the form of a thin wire and thefree end of which (lefthand end in FIG. 1) mechanically engages with theteeth of a ratchet 15 which it activates when the member 4 oscillates.This ratchet, or more particularly a pinion carried by its shaft,controls thev first wheel off the timing train. On each side of the reed4 in proximity to the support 8 are secured two small piezo-electriccrystals 7, and 7'. These piezo-electric crystals may, for example, beattached to the reed by means of an adhesive which is sufficientlyelectrically conductive. Thus the metallic reed 4 forms an electricalconnection between the two piezo-electric crystals 7 and 7 and functionsalso as one electrode (the interior'electrode) of each of thesecrystals. Thus the two interior electrodes of the crystals areelectrically connected. The opposed surfaces of the two piezo-electriccrystals 7 and 7 may also be metallized and be attached to the reed 4 bya substance which is not electrically conductive, the metallic coatingon the crystals which acts as electrodes being connected together and tothe reed 4 by conductors.

The drive winding 11 of motor 1, a battery 9 and the emitter-collectorpath of a transistor 10 are connected in series circuit relationship asshown in FIG. 1. The pickup winding 12 of motor 1, the battery 9 and theemitter-base path of transistor 10 are also connected in series circuitrelationship. The piezo-electric crystals 7 and 7' are connected inparallel across the windings l2 and 11 respectively of the motor. Thebase of the metallic reed 4 is connected to the negative pole of thebattery 9.

Connected in parallel across the two electrodes of each of crystals 7and 7 are resistors 13 and 14 respectively. The characteristics and typeof the transistor 10 determine if the two resistors 13 and 14 arenecessary, or if only one of these is necessary, or if neither arenecessary.

When the motor 1 is connected to the battery 9 and commences to rotatein one direction or the other, the reed 4 will be caused to oscillate bythe magnetic interaction between the magnets 3 of the rotor 2. and themagnet 6 of the reed. After a short time the reed begins to oscillatewith a frequency determined by the material of which it is constructedand by its dimensions and the motor begins, for example after onesecond, to rotate with a fixed speed of rotation corresponding to thefrequency of oscillation of the reed 4.

The stabilization of the speed of rotation of the motor, the value ofwhich is determined by the frequency of oscillation of the reed 4, isexpedited and improved by the impulses produced by the frequency of themechanical oscillations of the reed 4 which impulses are received by thecontrol circuit including transistor and which are superimposed on thepulses produced in he pickup winding 12 by the magnets of the rotor 3.

The circuit of FIG. 1 has the advantage that the metal reed 4 mayconsist of an alloy having a very small coefficient of temperature, forexample the reed may be made of an well known alloy sold under the nameNIVAROX the temperature coefficient of which is practically zero. Thepiezo-electric crystals 7 and 7 may be relatively small which reducestheir cost and also reduces their sensitivity to changes of temperatureto practically negligible proportions. However, it is possible to formthe reed 4 of a suitable synthetic plastic material instead of metal.When the reed 4 is formed of plastic material the electrical connectionsbetween the two opposed, internal surfaces of the piezo-electriccrystals 7 and 7 may be affected by providing a metallic layer on thereed 4 to which layer the negative pole of the battery 9 is alsoconnected.

Referring now to FIG. 2, in which the reference numerals 22, 23, 21, 31,26, 28, 29 and 30 indicate the same parts or members as the referencenumerals 2, 3, 1, 11, 6, 8, 9 and 10 respectively of FIG. 1, the reed 4(FIG. 1) is replaced by a piezo-electric crystal 24 embedded at itslower end in the support 28. The upper, free end of the crystal 24carries a permanent magnet 26 disposed in close proximity to the magnets23 situated around the circumference of the rotor 22 of the motor. Theshaft 21 of the rotor carries a pinion 25 which serves to actuate thefirst wheel of the timing train. In this embodiment of the inventionalso, the drive winding 31 of the motor, the battery 29 and theemitter-collector path of the transistor 30 are arranged in seriescircuit relationship. By means of metal contacts 32 and 32' the crystal24, the battery 29 and the emitter-base path of the transistor 30 arealso connected in series circuit relationship. This embodiment of theinvention functions without a pickup winding for the motor because thecontrol impulses necessary for feeding to the transistor 30 are producedby the crystal 24. In the arrangement of FIG. 2, it is equally possible,but in no sense mandatory, to connect the field winding of the motor inparallel or in series with the crystal 24 in a manner somewhat similarto that shown in the embodiment of FIG. 1 and FIG. 3 respectively.

In this embodiment of the invention the member 24 instead of being acrystal may also consist of a reed of metal or plastic embedded in thesupport 28 and as referred to in connection with FIG. 1. If the member24 consists of such a metal or plastic reed, a crystal would be fixed toone or the other side of such reed.

Given a certain frequency of oscillation of the member 4 or 24,thenumber of revolutions per unit time of the rotor 2 or 22 naturallydepends on the number of magnets 3 or 23 disposed around thecircumference of the rotor. If all the magnets of the rotor have likepoles directed outwardly therefrom, the magnet 6 or 26 will be alwaysattracted or repelled by the magnets 3 and 23 respectively when thecorresponding rotor rotates. Alternatively, if the magnets 3 and 23 arearranged so that each alternate magnet presents a different pole towardsthe exterior, the magnets 6 or 26 will be alternatively attracted andrepelled by rotation of the corresponding rotor.

Referring again to FIG. 2, between the pinion 25 on the shaft of therotor 21 and the timing train may preferably be disposed a known clutcharrangement of the type used in watches having automatic winding andwhich clutch assures that the timing train will be always actuated insame sense independent of the direction of rotation of the motor. Also,such an arrangement effects economies in that accessories for assuringthat the motor always rotates in the same direction can be dispensedwith. Referring back to the embodiment of FIG. 1, the pawl 5 and theratchet 15 are able to be arranged in such a manner that at thecommencement of oscillation of the reed 4 the ratchet 15 will beactuated always in the same direction. In this embodiment also one mayinclude a clutch arrangement of the type mentioned above between theratchet 15 and the timing train.

By way of example only the dimensions of various members of theembodiment according to FIG. 1 may be as follows. The reed 4 may have alength of 18 mm and a thickness of 0.2 mm; the crystals 7 and 7 may havea length of about 5 mm when the diameter of the rotor 1 is about 10 mm.Therefore, the various members of the apparatus according to theinvention take up very little space and are particularly suited for usewith watches. With a battery voltage of l, 25 V the electric motor onlyconsumes a current of the order of 8 to 10 microamps, assuring that awatch will have a very great power reserve.

A device according to the invention permits, therefore, the fabricationof timepieces, particularly watches, in a simple and economic(inexpensive) manner yet in a manner which imparts a high workingprecision to such timepieces.

The invention is not limited to the two embodiments described above andvariations may be made in these embodiments without departing from thescope of the invention as defined herein.

For example, a second reed may be embedded in the support 8 or 28 andpurely resonant mechanical oscillations will be imparted to such reed bythe intermediary of the material of the support 8 or 28. With such anarrangement the stability of the oscillations and in consequence theirsynchronization effect will be improved still further. An embodimentcomprising a second reed 4' is shown in FIG. 3, which is otherwise quitesimilar to the embodiment of FIG. 1, corresponding parts of FIG'. 3,have the same reference numbers. The controlling member for the timingtrain is formed by a pinion 25 as in FIG. 2, and the pick-up winding 12is connected in series circuit relationship with the crystal 7. Thefirst mentioned reed 4 carrying a magnet 6 or a piece of soft steel willbe caused to oscillate by the rotor 2 of the motor while the second reed4' may take the form of piezo-electric crystal or carries crystal 7 and7 and serves as the transmitter of the control impulses. Equally, thepossibility is foreseen of having two resonantly oscillatable reeds eachcarrying a piezo-electric crystal, one such crystal (such as that ofFIG. 1) being connected in the control circuit and the other suchcrystal being connected in the motor circuit of a transistor in thisarrangement it is only necessary that one reed carries a magnet or pieceof soft steel.

What is claimed is 1. Control apparatus of an electric timepiece,particularly a watch, of thetype including an electric motorsynchronized by an oscillating device and the drive winding of saidelectric motor being connected in the motor .circuit of a transistor,and including a member controlling the timing train of the timepiece, inwhich apparatus the oscillating device includes a piezo-electric crystaland a piece of magnetic material which when oscillated causesoscillation of said piezoelectric crystal, said magnetic material beingdisposed in proximity to the circumference of a rotor fixed for rotationwith the electric motor and around the periphery of which rotor aredisposed one or more permanent magnets so arranged that rotation of therotor causes said magnetic material and said piezo-electric crystal tobe oscillated, said piezo-electric crystal being connected in thecontrol cricuit of said transistor so that electric impulses from theoscillating piezo-electric crystal are superimposed on the motor circuitof said transistor. I

2. Apparatus according to claim 1, in which said motor has a pickupwinding and in which said piezoelectric crystal is connected in parallelwith said pickup winding of the motor.

3. Apparatus according to claim 1 including a battery in series withsaid piezo-electric crystal and with the emitter-base path of saidtransistor, the drive winding of the electric motor being connected inseries with said battery and with the emitter-collector path of saidtransistor.

4. Apparatus according to claim 1, in which said motor comprises a shaftand in which said member controlling the timing train of the timepieceincludes a pinion secured on the shaft of the electric motor.

5. Apparatus according to claim 1, in which said member controlling thetiming train of the timepiece includes a ratchet and a pawl mounted foroscillation with said oscillating device and mechanically cooperatingwith said ratchet.

6. Apparatus according to claim 1, in which said oscillating devicecomprises an elongated piezo-electric crystal having said magneticmaterial connected to a free end thereof and including .a support forsaid crystal embedded in said support.

7. Apparatus according to claim 1, in which said oscillating devicecomprises an elongated reed, a support in which one end of said reed isembedded, said reed having said magnetic material connected to a freeend thereof, said piezo-electric crystal being secured to one side ofsaid reed.

8. Apparatus according to claim 7, including a second piezo-electriccrystal attached to said reed opposite to said first mentionedpiezo-electric crystal, said second piezo-electric crystal beingconnected in parallel with the drive windin of the electric motor.

9. Apparatus accro ing to claim 1,

including a second oscillating device comprising an elongated reedembedded in the same support as the first mentioned oscillating deviceso as to vibrate in resonance therewith.

10. Apparatus to claim 1, in which said motor comprises a'pickup windingand said piezo-electric crystal is connected in series with said pick-upwinding of the motor.

1. Control apparatus of an electric timepiece, particularly a watch, ofthe type including an electric motor synchronized by an oscillatingdevice and the drive winding of said electric motor being cOnnected inthe motor circuit of a transistor, and including a member controllingthe timing train of the timepiece, in which apparatus the oscillatingdevice includes a piezoelectric crystal and a piece of magnetic materialwhich when oscillated causes oscillation of said piezo-electric crystal,said magnetic material being disposed in proximity to the circumferenceof a rotor fixed for rotation with the electric motor and around theperiphery of which rotor are disposed one or more permanent magnets soarranged that rotation of the rotor causes said magnetic material andsaid piezo-electric crystal to be oscillated, said piezo-electriccrystal being connected in the control cricuit of said transistor sothat electric impulses from the oscillating piezo-electric crystal aresuperimposed on the motor circuit of said transistor.
 2. Apparatusaccording to claim 1, in which said motor has a pickup winding and inwhich said piezo-electric crystal is connected in parallel with saidpickup winding of the motor.
 3. Apparatus according to claim 1 includinga battery in series with said piezo-electric crystal and with theemitter-base path of said transistor, the drive winding of the electricmotor being connected in series with said battery and with theemitter-collector path of said transistor.
 4. Apparatus according toclaim 1, in which said motor comprises a shaft and in which said membercontrolling the timing train of the timepiece includes a pinion securedon the shaft of the electric motor.
 5. Apparatus according to claim 1,in which said member controlling the timing train of the timepieceincludes a ratchet and a pawl mounted for oscillation with saidoscillating device and mechanically cooperating with said ratchet. 6.Apparatus according to claim 1, in which said oscillating devicecomprises an elongated piezo-electric crystal having said magneticmaterial connected to a free end thereof and including a support forsaid crystal embedded in said support.
 7. Apparatus according to claim1, in which said oscillating device comprises an elongated reed, asupport in which one end of said reed is embedded, said reed having saidmagnetic material connected to a free end thereof, said piezo-electriccrystal being secured to one side of said reed.
 8. Apparatus accordingto claim 7, including a second piezo-electric crystal attached to saidreed opposite to said first mentioned piezo-electric crystal, saidsecond piezo-electric crystal being connected in parallel with the drivewinding of the electric motor.
 9. Apparatus accroding to claim 1,including a second oscillating device comprising an elongated reedembedded in the same support as the first mentioned oscillating deviceso as to vibrate in resonance therewith.
 10. Apparatus to claim 1, inwhich said motor comprises a pickup winding and said piezo-electriccrystal is connected in series with said pick-up winding of the motor.